SOFIA, Bulgaria 
The candidate of Bulgaria's ruling center-right party, Rosen Plevneliev, is favored to win in Sunday's presidential elections that test the government's popularity and the EU nation's ability to overcome concerns about vote-buying and corruption.

Voting was slow Sunday morning, with only 19 percent of the 6.9 million eligible voters casting their ballots by noon, the MBMD opinion research agency said.

Bulgaria's economic woes have been the key campaign issue, with the opposition accusing incumbents of stalling key reforms. The country will get a new president and heated mayoral battles are expected in many of the 264 municipalities.

International observers have already voiced concerns, however, about the fairness of Sunday's elections, and any fraudulent voting could deal a blow to Bulgaria's hopes of getting into Europe's passport-free Schengen travel zone. The EU so far has refused to include Bulgaria due to what it called widespread graft.

"There are fears about large-scale vote buying and manipulations in the counting of the ballots," the OSCE monitoring team said.

Graft watchdog Transparency International predicted that as many as 20 percent of the voters in the EU's poorest country could be persuaded to sell their ballots.

Most power in Bulgaria rests with the prime minister and Parliament, but the president leads the armed forces and can veto legislation and sign international treaties.

Bulgaria's current socialist president, Georgi Parvanov, has served two five-year terms and was barred from seeking re-election.

Parvanov admitted he has not succeeded in his quest for national unification, and pointed out that the current campaign has gone too far in creating confrontations that should have been dealt with a long time ago in people's minds.

"I hope elections will bring about a better future for the country, as well as for every single Bulgarian," he said.

Former Construction Minister Plevneliev is tipped by all polls as the front-runner with about 30 percent of the vote.

But opinion polls have indicated that none of the 18 presidential candidates is likely to win outright, requiring a runoff on Oct. 30.

The 47-year-old technocrat is supported by the governing GERB party of Prime Minister Boiko Borisov. An entrepreneur before entering politics in 2009, Plevneliev has pledged to reduce the country's budget deficit and pursue business-friendly policies.

"I know what to do about Bulgaria, the regions and the economy so it can be a respectable member of Europe, a respectable member of the world," Plevneliev said after casting his ballot.

A victory by Plevneliev could increase the chances that Borisov's minority center-right government pushes ahead with painful economic reforms in a country with an average monthly salary of euro350 ($485) and 11.7 percent unemployment. One labor union estimates that 20 percent of Bulgarian families are impoverished.

Plevneliev's closest rivals are Ivailo Kalfin, 47, of the opposition Socialist Party, and independent Meglena Kuneva, 54, a former European Union commissioner.